The prior art has provided much attention to the problem of arresting lateral swinging of the trailer portion of a tractor-trailer before a jackknifing occurs. Since the tractor and trailer must be free to angulate relative to each other for maneuvering purposes, it is neither possible to rigidly couple the tractor and trailer nor to provide constantly active angular movement limitation stops. One method of solution to this problem is to provide for arresting of relative angular movement of the tractor and trailer only in response to application of the service brakes of the vehicle. However, a rigid locking together of the tractor and trailer on application of the service brakes creates serious control instability for the driver.
In my prior patent, U.S. Pat. No. 4,452,466 issued June 5, 1984, I provided apparatus that, in response to application of the service brakes of the vehicle, would limit further relative angulation of the tractor and trailer within angular stops established by the limits of travel on an angularly shifting caliper brake device cooperating with a control ring carried by the tractor and coupled by a hitch to the trailer to be responsive to angulation of the trailer. Therein the caliper brake device would, in response to application of the service brakes, and increasing relative angulation of the tractor and trailer, tend to dissipate offensive rotational energy. However, the environment of the control ring has been such that it has been difficult to keep clean so that full braking power can be applied thereto by the caliper brake device.
My prior invention would benefit from a redesign of the braking device to provide for a higher degree of braking reliability. Furthermore, a more easily accomplished coupling not requiring the physical attachment of a hitch between the control ring and the trailer would also be beneficial. This invention is based, in part, on my Disclosure Document No. 167703, filed Apr. 6, 1987 and the amendment thereto by Disclosure Document No. 175957, filed Aug. 21, 1987.